Interesting and smart: Sen. Rand Paul taps into an American tradition of dissent rarely invoked by other modern Republicans. Photo: Reuters

You won’t find him on any Federal Election Commission disclosure forms, but Director of National Intelligence James Clapper is the biggest in-kind donor to the incipient Rand Paul-for-president campaign.

Whatever its merits, the National Security Agency metadata program couldn’t be better fashioned to play into fears of the government. Is it vast? Yes. Secret? Check. Raise profound questions about privacy? Uh-huh.

This is the kind of issue Rand Paul was born and (literally) raised to raise holy hell over. The NSA leak came on the heels of revelations that the Internal Revenue Service was singling out tea-party groups for extra scrutiny, and on the heels of the Associated Press and James Rosen investigations.

Add in the gun-control fight earlier this year and Paul is nearly 4-for-4 in fights sticking up, in his view, for the first four amendments of the Bill of Rights. The only thing missing is the third, because no one has proposed quartering of troops in our homes — yet.

It is a Rand Paul moment in the GOP not just because the headlines reinforce his core critique of leviathan as too big, too unaccountable and too threatening, but because he is smart and imaginative enough to capitalize on those headlines.

Paul has that quality that can’t be learned or bought: He’s interesting. How many potential Republican presidential candidates have helped shepherd a new verb into the English language. The hoopla around Paul’s filibuster gave us “to drone,” in the sense of “don’t drone me, bro.”

Paul taps into an American tradition of dissent not usually invoked by Republicans. At the Time magazine gala this year honoring the 100 most influential people in the world (he was one), he raised a glass to Henry David Thoreau. In his inaugural Senate address, he contrasted his Kentucky hero, the irascible abolitionist Cassius Clay, with the more conventional Kentucky political legend, the Great Compromiser, Henry Clay.

His cultural affect is different, too, a little more Utne Reader than National Review. At a packed event at the Reagan Library, he explained: “I’m a libertarian conservative who spends most of my free time outdoors. I bike and hike and kayak, and I compost.” It might be the first positive reference to composting in the history of that fine institution.

Not too long ago, Paul’s foreign-policy views would have been an insuperable obstacle to a serious presidential run. No more. The evolution in the party’s foreign policy is captured in the story of the Pauls. In 2008, Ron Paul’s noninterventionism made him a punching bag in the Republican primary debates. In 2012, it got a respectful hearing. In 2016, his son’s (less toxic) version of the same policy will be much closer to the party’s mainstream.

At least for some stretch of 2015, Rand Paul could well be the Republican front-runner, tapping into grass-roots enthusiasm on the model of Howard Dean in 2003. And it’s not inconceivable that he could go further than that famous representative of “the Democratic wing of the Democratic Party.”

Paul has a built-in online and grass-roots network of the sort it takes years to build. In fact, it did. His father built it, and now he’s working to expand it in his extensive travels. During those years, his father welcomed into his fold cranks and haters, and one of Rand Paul’s quiet messages is that he has his father’s core convictions, without the loathsome baggage.

I’m far from a Rand Paul-ite. I don’t think there was ever any threat of Americans being droned sitting at cafes, nor do I think drones are the scariest invention in the history of flight. I’m not where Paul is on foreign or national-security policy, and I doubt his libertarianism has as much crossover appeal in blue states as he hopes.

But libertarianism is a significant strand on the right. It should be represented, and represented well. By and large, Rand Paul does that. Underestimate him at your peril.